1. Field of the Invention
The present invention relates to a multi-plate clutch, including a clutch outer member, a clutch inner member, a pressure-receiving plate, a center cam, an assist cam, and a slipper cam which is substantially identical to the assist cam. More particularly, the present invention relates to a multi-plate clutch which is characterized in that the clutch outer member is connected to an input member, the clutch inner member includes a cylindrical portion coaxially disposed in the clutch outer member, and a pressure-applying plate portion provided integrally with one end of the cylindrical portion, and the pressure-receiving plate fixed to an output member. Further, the present invention is characterized in that a plurality of driving friction plates engaged with the clutch outer member so as not to rotate relative thereto, and a plurality of driven friction plates engaged with the clutch inner member so as not to rotate relative thereto are interposed between the pressure-receiving plate and the pressure-applying plate portion, the center cam has a disc portion disposed in a plane orthogonal to a rotation axis of the output member, and is disposed inward in a radial direction of the cylindrical portion and fixed to the output member, the assist cam is arranged opposite to one surface of the disc portion, and is operable to move the pressure-applying plate portion toward the pressure-receiving plate based on an increase in driving force inputted from the input member, and the slipper cam is arranged opposite to the other surface of the disc portion, and is operable to move the pressure-applying plate portion away from the pressure-receiving plate based on an increase in back torque from the output member.
2. Description of the Background Art
There is a known multi-plate clutch in which an assist cam, a slipper cam, and a clutch inner member are fastened together with multiple bolts. An example such multi-plate clutch is disclosed in the Japanese Patent Application Publication No. 2008-38954.
The assist cam is arranged opposite to one surface of a center cam fixed to an output member, and thus constitutes an assist cam mechanism by cooperating with the center cam. The slipper cam is arranged opposite to the other surface of the center cam, and thus constitutes a torque limiter mechanism by cooperating with the center cam.
However, in the multi-plate clutch as disclosed in the Japanese Patent Application Publication No. 2008-38954, in order to ensure strength sufficient to withstand torques generated in the assist cam mechanism and the back torque limiter mechanism, it is necessary to use high-strength bolts or increase the number of bolts. This may cause increase in the cost, and increase in weight of bolts.
The present invention has been made to overcome such drawbacks of the existing multi-plate clutch. Accordingly, it is one of the objects of the present invention to provide a multi-plate clutch in which torques can be transmitted from an assist cam and a slipper cam to a clutch inner member without using bolts, and in which the number of components of the multi-plate clutch, and the cost are reduced, and which has a low weight.